Felton, meanwhile, was basking in the cast reunion. "It's great seeing everyone again," he says. "We've all been catching up – I love it."

The expansion, which opens to the public on July 8, includes among its many features a new thrill-ride attraction based on the escape sequence from Gringotts wizarding bank in J.K. Rowling's seventh novel, Harry Potter and the Deathly Hallows.

Fans of the blockbuster book and film series may also ride the scarlet Hogwarts Express train from London's Kings Cross Station to Hogsmeade – with visual effects worthy of a wizard along for the special journey.

The Wizarding World of Harry Potter's Diagon Alley

James Kilby / Universal Orlando Resort / Getty

Also among the Potter stars in attendance: Matthew Lewis, who played shy but brave Neville, James and Oliver Phelps (prankster twins Fred and George Weasley), Robbie Coltrane (Hagrid) and Warwick Davis. (Daniel Radcliffe, Emma Watson and Rupert Grint skipped the event, while joining Bonham Carter – and the festivities – was director Tim Burton.)

The new Diagon Alley, which includes the Leaky Cauldron pub, Florean Fortescue's Ice Cream Parlour and Weasleys' Wizard Wheezes, to say nothing of a fire-breathing dragon, "is even more true to life than the movie sets," says Evanna Lynch, who played dreamy Luna on screen.

"I just wish they could figure out a way to have gnomes running around, biting your heels. Wouldn't that be fun?"

The Wizarding World of Harry Potter;s Diagon Alley

James Kilby / Universal Orlando Resort / Getty

FLASHBACK: The Stars Hit the Red Carpet at the Premiere of Harry Potter